As the role of computers has expanded in society, various different techniques have been developed for entering data into computers. One particularly useful technique for submitting data is through handwriting. By writing with a stylus or another object onto a digitizer to produce “electronic ink,” a computer user can forego the bulk and inconvenience associated with a keyboard. Handwriting input conveniently may be used, for example, by doctors making rounds, architects on a building site, couriers delivering packages, warehouse workers walking around a warehouse, and in any situation when the use of a keyboard would be awkward or inconvenient. While handwriting input is more convenient than keyboard input in many situations, text written in electronic ink typically cannot be directly manipulated by most software applications. Instead, text written in electronic ink must be analyzed to convert it into another form, such as ASCII characters. This analysis includes a handwriting recognition process, which recognizes characters based upon various relationships between individual electronic ink strokes making up a word of electronic ink.
Handwriting recognition algorithms have improved dramatically in recent years, but their accuracy can be reduced when electronic ink is written at an angle. Likewise, when separate groups of ink strokes cannot be easily distinguished, such as when two words are written closely together, many recognition algorithms cannot accurately recognize electronic ink. Some recognition algorithms also may incorrectly recognize electronic ink as text when, in fact, the electronic ink is intended to be a drawing. For example, a user may annotate typewritten text by writing an electronic ink stroke that underlines, highlights, circles or crosses through some portion of the typewritten text. A handwriting recognition algorithm might then incorrectly recognize these annotation strokes as a dash, the number zero or the letter “O.”
The accuracy of many recognition algorithms can be greatly improved by “parsing” (e.g., by analyzing the layout of and/or “classifying”) the electronic ink before using the handwriting recognition algorithm. A classification process typically determines whether an electronic ink stroke is part of a drawing (that is, a drawing ink stroke) or part of handwritten text (that is, a text ink stroke). Classification algorithms for identifying other stroke types also are possible. The layout analysis process typically groups electronic ink strokes into meaningful associations, such as words, lines and paragraphs. Layout analysis and classification processes can thus be used to identify which strokes in a collection of electronic ink belong to a single word, which words of the electronic ink are associated with a single line of text written in electronic ink, and which lines of text written in the electronic ink are associated with a paragraph.
While layout analyzing and classifying ink can dramatically improve the recognition of electronic ink, many software application developers are unaware of the importance of these activities before recognizing the electronic ink. Until recently, layout and classification algorithms were not readily available for use with existing software applications. For example, the Microsoft® Windows XP Tablet PC Edition Version 2002 operating system was typically sold with the Microsoft® Windows Journal software application for storing, displaying and manipulating electronic ink. While the Microsoft® Windows Journal software application employs an internal parser, until recently this parser was not accessible to other software applications run by the operating system.
While the parsing process from the Windows Journal software application is now separately accessible by other software applications, the use of this parser is not well known, and this parser cannot easily be employed with many software applications, into which a user may desire to enter handwriting input. Moreover, even if a software application developer were to create a parser specifically for use with a desired software application (which itself may be a difficult and time-consuming process), execution of a parsing process may be quite time-consuming. For example, parsing just a few strokes of electronic ink using a relatively fast microprocessor may take a parser several seconds or even several minutes. If a software application must halt operation until the parsing process is complete, the software application will become too slow for practical use by most users.
Accordingly, there is a need for electronic ink processing techniques that can be employed by a variety of software applications to, for example, analyze the layout of, classify, and/or recognize electronic ink. Further, there is a need for electronic ink processing techniques that can process electronic ink while still allowing the software application employing the techniques to accept new electronic ink input without invalidating the results of the ink processing.